The invention relates to an internal combustion engine comprising at least one combustion chamber in a cylinder head covering at least one cylinder, and having at least one intake passage and one exhaust passage extending through the cylinder head, and an exhaust gas recirculation passage which branches off the exhaust passage and opens at least into one intake passage.
For the design of modern internal combustion engines, increasingly ecologically based requirements are to be taken into account, for example a reduction in the emission of pollutants. The pollutant emissions can be markedly reduced through the use of high-grade catalytic converters. However, it is expedient to not only subsequently treat the exhaust gases leaving the internal combustion engine by means of a catalytic converter, but to also achieve better fuel consumption during actual engine operation by design measures. The quantity of the exhaust gas components which are problematical for the environment can already be considerably reduced before leaving the engine by virtually complete combustion of the fuel.
A known method of reducing the emissions is external exhaust gas recirculation.
With exhaust gas recirculation, in which at least some of the exhaust gases are directed back into the combustion chamber, virtually complete combustion of hydrocarbons, hitherto not completely burned, is achieved. Furthermore, a reduction in the nitrogen oxide emissions can thus be effected.
DE695 17 938 T2 discloses an arrangement for exhaust gas recirculation for an internal combustion engine. The internal combustion engine has at least one combustion chamber and also at least one intake passage and an exhaust passage. An exhaust gas recirculation passage opens out into at least one of the intake passages, a flap being arranged on its intake-passage-side part, this flap being arranged on the wall of the intake passage and being pivotable transversely to the intake passage. According to an embodiment variant, the flap, in its one end position, with an intake-passage-side surface thereof, it bears laterally against the intake passage in such a way as to be flush with adjacent wall parts of the intake passage, whereas, in its other end position, it forms a ramp-like and continuous constriction with the intake-passage-side surface in the intake passage. The exhaust gas recirculation passage is shut off in the one end position and is connected to the intake passage in the other end position. A flow of exhaust gases through the exhaust gas recirculation passage can be controlled by adjusting the flap, it being possible for a simple valve, for example in the form of a slide valve of the yes/no type, to be arranged on the inflow side for assisting the flap control, so a to ensure reliable shut-off of the exhaust gas recirculation.
EP 1 002 947 A1 discloses a first throttle flap for regulating the exhaust gas recirculation, this throttle flap being arranged just upstream of, or at the point at which, an exhaust gas recirculation passage opens into an intake passage. Arranged in the intake passage preferably orthogonally to the first throttle flap described above is a second throttle flap coupled to the first throttle flap. The common pivot axis of the two throttle flaps crosses both the exhaust gas recirculation passage and the intake passage. Due to the preferably orthogonal arrangement of the two flaps relative to one another, the air flow in the intake passage is throttled to the maximum extent when the first throttle flap is completely open.
JP 10077914 A discloses a slide valve for opening or closing an exhaust gas recirculation passage opening into an intake passage for an internal combustion engine. In this case, the slide valve is adjusted in a translatory manner transversely to the intake passage and thus is inserted into or drawn out of an exhaust gas recirculation passage extending transversely to the intake passage. In the inserted state, the slide valve does not form any disturbing contour projecting into the intake passage, but the slide rod required for actuating the slide valve does form such a disturbing contour.
DE 199 27 673 A1 discloses a changeover device for changing over an air feed of an internal combustion engine. In this case, each combustion chamber of the internal combustion engine has a controllable and a non-controllable air feed passage and also a controllable passage for an exhaust gas feed. The latter passage receives air via a branch of the non-controllable air feed passage of the adjacent combustion chamber. Furthermore, a rotary slide valve member with two slide valves arranged on a common rotary shaft is provided, this rotary slide valve member controlling the controllable passages of the respective combustion chamber in opposite directions.
EP 0 855 502 A2 discloses an internal combustion engine having an exhaust gas recirculation arrangement. Here, either a translatory movable slide valve or a rotary slide valve is arranged in a wall of the induction passage, of the exhaust gas recirculation passage just upstream of the orifice for metering the quantity of the recirculated exhaust gas relative to the rest of the combustion air.
DE 199 00 640 C1 discloses an exhaust gas recirculation system for a multi-cylinder internal combustion engine. In this case, the exhaust gas recirculation flow is set with shut-off flaps which are arranged in the individual induction lines and the operation of which is coupled via a drive shaft, so that they can be operated simultaneously. In this case, the shut-off valves are used both for quick stopping and for setting the recirculated exhaust gas flow. Arranged parallel to these induction lines are further induction lines which are provided for feeding air and not for feeding exhaust gases.
DE 196 33 603 C1 discloses an internal combustion engine having in each case at least two intake passages for each cylinder. These intake passages branch off from a common induction passage. An exhaust gas recirculation passage opens at least into one of the intake passages. The exhaust gas recirculation passage and the intake passage connected to it are designed in such a way that they can be shut off. To this end, a rotary slide valve having a rotatable shut-off cylinder is arranged in the region where the exhaust gas recirculation passage opens into the intake passage. Depending on the rotary position, the shut-off cylinder can keep the intake passage to the cylinder open, open up a connection of the exhaust gas recirculation passage via the rotary slide valve to the cylinder when the intake passage is shut off, or totally shut off the exhaust gas recirculation passage and the intake passage.
DE 100 32 562 A1 discloses an internal combustion engine having exhaust gas recirculation in which the exhaust gas recirculation lines branch off directly from the cylinders, in the region of a bottom dead center of the piston, and are controlled solely by the respective piston.
DE 27 40 465 A1 discloses an internal combustion engine having intake and exhaust lines arranged on the same side and having exhaust gas recirculation which can be actuated as a function of pressure. To this end, a connecting passage is arranged in the cylinder head of the internal combustion engine by a dividing wall which separates an exhaust passage and an intake passage. Inserted in the connecting passage is a spring-loaded valve which serves to regulate the exhaust gas quantity flowing into the combustion chamber. On account of the intake and exhaust passages arranged on the same side of the internal combustion engine, no additional lines are therefore required for the exhaust gas recirculation.
For exhaust gas recirculation on an internal combustion engine, it is known from DE 196 42 685 A1 to provide a manifold in a dividing plane between cylinder head and crankcase, this manifold being connected via branch passages in the cylinder head to the intake and exhaust passages of the internal combustion engine. Arranged between the exhaust- and intake-passage-side parts of the manifold is a valve which controls the exhaust gas flow from the exhaust side to the intake side. Due to the arrangement of the manifold in the dividing plane between the crankcase and the cylinder head, the hot exhaust gas in the manifold is cooled by the engine cooling system.
It is the object of the present invention an improved internal combustion engine of the type mentioned initially, including improved means for the metering of the exhaust gas recirculation and the stratification of the exhaust gases in the combustion chamber.